The grim reality began to settle in at the White House yesterday as a parade of House Republicans stepped forward to announce their votes on impeachment: What seemed unthinkable only a few weeks ago suddenly appeared almost inevitable.

White House officials and their Democratic allies struggled for a last-minute maneuver that might spare President Clinton from becoming the second president in U.S. history to be impeached by the House.

But a White House long praised for its tactical political skills now found itself hamstrung by the mounting arithmetic in the House.

As each additional Republican announced in favor of impeachment, the president's options dwindled. What made sense when there were two dozen or more Republicans in the House who had not declared their intentions -- one final, dramatic appeal for mercy by the president, for example -- seemed futile if there were no longer enough votes left to change the outcome.

"I don't see any hope here," one congressional Democrat said late yesterday afternoon, after nine Republicans announced their intentions to support impeachment and a 10th switched his position after announcing earlier he would vote against.

"The bottom's dropping out," said one outside adviser to the White House.

No one at the White House was prepared to give up the fight, despite the steady shrinkage of potential GOP votes against impeachment. "I still think we have a shot at it," a senior administration official said. "People are still working at it."

With Clinton en route back from Israel yesterday afternoon, the president's allies refused to concede defeat. "Every member you call has another solution or another scheme," one administration official said, adding, "There's no consensus. You will hear 10 different approaches that even the members don't agree with."

As they weighed ideas coming in from friends on the outside and mulled some of their own, none of the president's advisers underestimated how badly his situation had deteriorated during his brief trip to the Middle East.

A former administration official who has been in close touch with senior White House advisers said, "I'm not being fatalistic but there's no dynamic that changes this."

Then, in a sarcastic reference to the decision by the House GOP leadership to prevent a censure vote on the House floor this week, he added, "Everybody's allowed to vote on [House Majority Whip] Tom DeLay's conscience. I think censure would win, but that's not an option. . . . I don't know what you can do to switch the dynamic."

"I want to remain respectful to these members," one senior White House official said of the House Republicans. "But this has less and less to do with law and logic. If you ask me, it's more and more to do with emotion and politics."

White House officials shuttled through an endless series of meetings and telephone calls. Some traveled to Capitol Hill for a meeting with Democratic allies. They sought to focus public and news media attention on what they said was the enormous pressure applied to the undeclared Republicans by their leadership. And they continued to warn that Republicans could pay a high price politically by defying public opinion and voting to impeach the president.

But as the day unfolded, White House officials recognized that the skills they had honed in countless battles in behalf of Clinton were ineffective in the current fight. They have excelled at the outside game of politics and winning the battle of public opinion.

But the Republican majority in the House appeared impervious to national opinion polls. And the White House has found few weapons effective in waging the inside battle in the House.

Some Democrats in Congress urged Clinton to make a dramatic appearance in the well of the House. Others suggested expanding a scheduled meeting this morning with Rep. Christopher Shays (R-Conn.) to include other moderate Republicans still making up their minds. But neither option appeared attractive by the end of the day.

"If the pool [of Republican votes] dwindles below what you need, what's the point?" asked a Democratic ally of the president. "Unless you can say something so dramatic you can pull people back who say they're going to vote for impeachment."

Vice President Gore was enlisted to help make telephone calls, but by yesterday morning still had not received a call list. In the end, he spoke only to Democrats still thought to be undecided -- not the crucial group of moderate Republicans who have been so much the focus of attention. Gore also tried to encourage a couple more op-ed pieces that might help to create the climate for a censure resolution.

Given the steady erosion in Clinton's standing, his supporters braced for what they expect to be the next battle in the long war with the Republicans. If House Republicans approve one or more of the four articles of impeachment later in the week, the president's allies expect calls for him to resign to spare the country the anguish of a trial in the Senate.

"The next move will be an enormous campaign to make the president resign," one administration official predicted.

The GOP strategy, Democrats believe, is obvious: It is the president and not the Republicans now dragging out the process. In the past, Clinton has called for a speedy conclusion, even if that involves a stiff censure resolution. Now, Democrats say, the Republicans may attempt to turn the tables on the White House.

White House officials restated Clinton's opposition to resignation. "One party must not be allowed to force a president of the other party out of office because it would fundamentally change the way in which we choose our leaders and put us on a path toward a parliamentary system of government," said White House spokesman Jim Kennedy. "That would be an outrageous result and it's not going to happen."

Rahm Emanuel, who recently left the White House for the private sector, argued that House Republicans already have lowered the standard for what constitutes an impeachable offense. "What would be worse, or equally damaging, is the idea that the way out of it is resignation," he said. "We're going down a nutty road and I think that would be equally harmful to the country."

Clinton's advisers cling to the hope for a censure resolution, but it appears more likely as an option once the House has acted on the impeachment articles. Administration officials praised the proposal advanced by former Senate majority leader Robert J. Dole (R-Kan.) in the New York Times yesterday and the call by Rep. Michael N. Castle (R-Del.) for a compromise resolution on the House floor.

But the speed with which the pro-impeachment forces have coalesced in the past two weeks has unnerved the White House team. They remain certain that the Senate will not vote to convict the president, if the House votes impeachment. But what they know better today than they did before is that they must think the unthinkable and prepare for it.